A separation method for separating a desired component from a mixed gas has been conventionally known. For example, Patent Document 1 discloses one example of such a separation method as follows.
Patent Document 1 below discloses a method for separating and recovering carbon dioxide as a desired component from an exhaust gas, which is a mixed gas. Further, Patent Document 1 discloses, as a separation device for carrying out the separation and recovery method, a carbon dioxide recovery device comprising an absorption tower for absorbing carbon dioxide in the exhaust gas into an absorption liquid and a regeneration tower for separating and recovering carbon dioxide from the absorption liquid having absorbed carbon dioxide in the absorption tower and regenerating the absorption liquid into a fresh state. In the absorption tower, carbon dioxide in the exhaust gas is absorbed in the absorption liquid by bringing the exhaust gas into contact with the absorption liquid. Then, in the regeneration tower, the absorption liquid having absorbed carbon dioxide in the absorption tower is heated for the purpose of releasing and separating carbon dioxide from the absorption liquid, thus the absorption liquid is regenerated. The regenerated absorption liquid is then used again for absorbing carbon dioxide in the absorption tower. Subsequently, this whole process is repeated.
However, a conventional separation method requires a large amount of energy for heating the absorption liquid for the purpose of releasing carbon dioxide from the absorption liquid in the regeneration tower. Further, in the absorption process for absorbing carbon dioxide into the absorption liquid in the absorption tower, an absorption amount of carbon dioxide per unit liquid volume of the absorption liquid is small, thus an absorption efficiency is poor. In order to secure a sufficient absorption amount of carbon dioxide in such an absorption process, it is necessary to increase a liquid volume of the absorption liquid, which in turn requires an increase in size of the separation device.